In optical imaging systems, such as laser printers, using optics modules, it is very important to properly align the optics module to the film plane of the imaging unit. Failure to do so will result in a misalignment of the image to the film or in a focusing error. Proper alignment is typically done in one of two ways. The optics module is either aligned in the machine in which it will be used, or it is aligned in an alignment fixture outside of the machine and then transferred to the machine.
U.S. Pat. No. 4,318,135, issued Mar. 2, 1982, inventors Allis et al., discloses an alignment system for scanning arrays. A linear array of photosensitive elements is mounted on a carrier which is in turn attached to a floating block. Threaded members can be moved in engagement with the block to provide adjustment of the array in three degrees of freedom in the plane of the array. The blocks can be adjusted in a plane perpendicular to the plane of the array by means of axially extending screws. One problem of the mount shown in this patent is that adjustment of any one of the threaded members produces motion of the array in more than one degree of freedom. This results in interactive adjustments requiring an interactive process which is difficult and time consuming.
Other optical device alignment techniques are disclosed in the following patents: U.S. Pat. No. 4,972,079 (corresponding to WO 91/01507), issued Nov. 20, 1990, inventor Blanding, discloses a mount for an optical device, such as a linear CCD array. The array is mounted on a base which is supported on a frame for adjustment relative thereto. The base is slidably movable on the frame for adjustment of the array in in-track and cross-track directions. The base is movable toward and away from the frame. Adjustment screws are provided to carry out adjustments.
U.S. Pat. No. 5,214,441, Issued May 25, 1993, inventors Blanding et al., and U.S. Pat. No. 5,294,943, issued Mar. 15, 1994, inventors Blanding et al., discloses techniques for aligning scan line optics with a target medium, such as a recording medium.
One of the problems disclosed in U.S. Pat. No. 4,972,079, issued Nov. 20, 1990, inventor Blanding, is that adjustment in any one axis of an alignment fixture is likely to affect the other axes. They disclose a method to prevent such axis cross-talk. However, no method is given for ensuring accurate repositioning of the aligned optics module within the machine. Similarly, problems disclosed in U.S. Pat. No. 5,294,943, issued Mar. 15, 1994, inventors Blanding et al., and U.S. Pat. No. 5,214,441, issued May 25, 1993, inventors Blanding et al., address a method to ensure accurate repositioning of the aligned module, but they do not address a method for preventing cross-axis talk.